Last month I took a Ryanair flight to Alicante and back. Three weeks after returning, the airline has charged my Visa account an extra £1.35, citing the same reference number to the original booking. The charge could have been much higher and I am very uneasy about retrospective charges over which I have no control or knowledge. RD, Birmingham

This is a rare Ryanair letter that can be easily explained. Air passenger duty was increased by the Spanish government at the end of June and applied to flights departing from Spanish airports on/after 1 July. It is this money that Ryanair took from your account. An email explaining the situation wouldn't have hurt. It must have cost them almost as much to collect such a small sum.

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